The present invention is directed to an artificial heart apparatus with an energy recovery circuit.
U.S. Pat. No. 5,674,281 to Snyder discloses an artificial heart assembly having a blood inlet conduit, a blood outlet conduit, and a pumping mechanism that pumps blood from the blood inlet conduit to the blood outlet conduit. The Snyder artificial heart assembly includes a first membrane defining a blood chamber fluidly coupled to the blood inlet conduit and the blood outlet conduit, and the pumping mechanism includes a pusher plate that makes contact with the first membrane to force blood from the blood inlet conduit to the blood outlet conduit. The Snyder artificial heart assembly also has a second membrane defining a second blood chamber fluidly coupled to a second blood inlet conduit and a second blood outlet conduit and a second pusher plate that makes contact with the second membrane to force blood from the second blood inlet conduit to the second blood outlet conduit.
U.S. Pat. No. 5,728,154 to Crossett, et al. discloses an artificial heart assembly that has a structure similar to the artificial heart assembly described above in connection with the Snyder patent. The Crossett, et al. patent also discloses a communications system that includes an external transceiver located external of a subject and an internal transceiver that is implanted beneath the skin of a subject. The internal transceiver is provided with an internal coil.
U.S. Pat. No. 5,751,125 to Weiss discloses an artificial heart assembly, which is provided either as a total artificial heart or as a ventricular assist device, having a sensorless motor and a circuit for reversibly driving the sensorless motor.
U.S. Pat. No. 5,630,836 to Prem, et al. discloses a transcutaneous energy and data transmission apparatus for a cardiac assist device such as an artificial heart or ventricular assist device. The transmission apparatus has an external coupler in the form of a tuned circuit with an induction coil and an internal coupler which together act as an air-core transformer. The transmission apparatus has a DC power supply and a power converter that are coupled to the external coupler. The power converter converts electric current from the DC power supply into high-frequency AC. The transmission apparatus has a voltage regulator coupled to the internal coupler. As shown in FIG. 3 and described in connection therewith, the Prem, et al. patent discloses that the voltage regulator includes a shunt switch and a shunt controller. As shown in FIG. 2, the power converter includes an H-bridge inverter, an H-bridge controller, and a shunt detector. The H-bridge controller can reduce the duty cycle of the H-bridge converter if a shunt is detected.
The invention is directed to an apparatus for use in an artificial heart assembly having a blood inlet conduit, a blood outlet conduit, and a pump that is adapted to pump blood from the blood inlet conduit to the blood outlet conduit. The apparatus includes an internal coil adapted to be implanted beneath the skin of a subject and an external coil adapted to be disposed adjacent the internal coil and separated from the internal coil by the skin of the subject, the external coil being coupled to transmit electric power to the internal coil through the skin of the subject.
The apparatus includes a DC-to-AC converter coupled to the external coil and to a source of DC power. The DC-to-AC converter selectively converts DC power from the DC power source into either a first frequency or a second frequency, the first frequency having a plurality of cycles each of a first duration and the second frequency having a plurality of cycles each of a second duration longer than the first duration.
The DC-to-AC converter comprises a first switching component coupled in parallel with a first passive component, a second switching component coupled in parallel with a second passive component, a third switching component coupled in parallel with a third passive component, a fourth switching component coupled in parallel with a fourth passive component, and a drive circuit operatively coupled to the switching components. The drive circuit causes all four of the switching components to be switched to a nonconductive state so that the four switching components are nonconductive for a time period and so that electric current flows through a plurality of the passive components during that time period.
The drive circuit may cause all four of the switching components to be switched to a nonconductive state for a time period at least as long as the first duration, or for a time period at least twice as long as the first duration.
The first switching component may be connected to the second switching component at a first junction, the second switching component may be connected to the third switching component at a second junction, the third switching component may be connected to the fourth switching component at a third junction, and the fourth switching component may be connected to the first switching component at a fourth junction. The fourth junction may be connected to the DC power source, the second junction may be connected to a ground potential, and the external coil may be connected between the first and third junctions. The switching components may comprise transistors, and the passive components may comprise diodes.
The features and advantages of the present invention will be apparent to those of ordinary skill in the art in view of the detailed description of the preferred embodiment, which is made with reference to the drawings, a brief description of which is provided below.